1. Field of the Invention
The invention relates in general to a light emitting element, and more particularly to a manufacturing method of a solid state light emitting element.
2. Description of the Related Art
The light-emitting diode (LED) emits a light by converting electric energy into photo energy. The LED is mainly composed of semiconductors. Of the semiconductors, those having a larger ratio of holes carrying positive electricity are referred as P type semiconductors, and those having a larger ratio of electrons carrying negative electricity are referred as N type semiconductors. The junction connecting a P type semiconductor and an N type semiconductor forms a PN junction. When a voltage is applied to the positive polarity and negative polarity of an LED chip, the electrons and the holes will be combined and emit energy in the form of a light.
In the manufacturing method of a light emitting diode formed by gallium nitride (GaN), sapphire is used as an epitaxy carrier, a buffer layer is formed on the sapphire substrate first, and then GaN is formed on the buffer layer. By doing so, the quality GaN epitaxial growth layer may thus be obtained. However, the sapphire substrate has poor performance in conductivity and heat-dissipation. To improve the heat-dissipation efficiency of the light emitting diode, the GaN epitaxial growth layer must be transferred to a substrate with better performance in conductivity and heat-dissipation. According to the conventional manufacturing method, the sapphire substrate disposed underneath the GaN epitaxy layer is removed by the excimer pulse laser beam process, that is, the generally used laser lift-off process. However, the laser lift-off process is highly complicated and the laser light may easily damage the GaN epitaxy. Therefore, how to improve the existing manufacturing process such that the GaN epitaxy may be separated from the sapphire substrate without causing any damage to the epitaxial growth layer has become a prominent task for the industries.